In Nathan Popple-v-Brimingham Women's NHS Foundation Trust [2012 EWCA Civ 1628 the Court of Appeal commented that the result of the appeal was of interest to the parties only. In fact it contains a short passage on causation and the application of Bailey-v-MOD which is of general interest.
According to the Court of Appeal's judgement, Nathan Popple suffered from "intra-partum asphyxia causing brain damage of the 'acute profound' or 'acute near total hypoxic' (low oxygen in the arterial blood) ischaemic (blocked or restricted blood supply) type as a result of which he now suffers severe dyskenitic or athetoid cerebral palsy". He therefore suffered from a single injury (Cerebral Palsy) due to a single cause (hypoxic ischaemic asphyxia, "HIA").
Nathan was born at 1449 hours. The failure adequately to monitor the fetal heart rate and nature of the other evidence in the case was such that the experts could not precisely determine the period of HIA. The evidence could not establish whether by Nathan suffered 15 minutes or 20 minutes of HIA. It appears to have been accepted that the period of HIA ended at birth (1449). The Court of Appeal noted that "the causation experts agreed that "Nathan would need to have been delivered between 1439 and 1444 in order to have avoided brain injury."" [paragraph 76]. If he had suffered a 15 minute period of HIA at birth then the HIA began at 1434, thus, delivery at 1444 would have limited him to a period of ten minutes of HIA. If he had suffered a 20 minute period of HIA then HIA began at 1429 hours and delivery at 1439 would have limited him to a period of ten minutes of HIA. A period of ten minutes of HIA would not have caused him any injury.
In fact the trial judge had held that but for the negligence of the midwives who had conduct of Nathan's mother's labour and his delivery, "I am satisfied that an episiotomy should have been performed by no later than 14.35 and that Nathan would have been delivered then or shortly thereafter - and, in any event, before 14.39." Thus, but for the negligence, he would not have had more than ten minutes of HIA and would not have suffered any injury at all.
Nevertheless the Court of Appeal did address the "what if" question. What if Nathan had in fact suffered a 20 minute period of HIA by birth at 1449 hours but, in the absence of the negligence, he would been been delivered by 1444 hours? He would then have suffered 15 minutes of HIA, the last five minutes of which would have caused injury, albeit less extensive injury than he in fact suffered (the severity of cerebral palsy would be generally considered to correlate to the duration of the HIA).
The Court of Appeal held at :
... Some damage might have occurred during the five minute period prior to 14.44 if the overall duration of the insult was 20 minutes, but there would still have been damage in the entire last five minutes from which Nathan would have been saved had he been delivered by 14.44. It was not possible to say how much, if any, damage occurred prior to 14.44, whereas all of the period thereafter must have been damaging. Thus, on any view, a failure to deliver by 14.44 either caused the damage in its entirety or made a material and probably preponderant contribution to it.
"In a case where medical science cannot establish the probability that 'but for' an act of negligence the injury would not have happened but can establish that the contribution of the negligent cause was more than negligible, the 'but for' test is modified, and the claimant will succeed."
Here the negligent failure to deliver Nathan before 14.44 caused all the damage if this was a 15 minute insult. Medical science cannot establish whether it was a 15 minute insult or a 20 minute insult. If it did take 20 minutes, the damage done in the last five minutes must have made a contribution to the overall harm which was more than minimal. I cannot see why the Bailey principle does not apply."
The medical uncertainty was about the actual period of HIA. As I understand it, there was no uncertainty about whether a period of HIA longer than 10 minutes would have caused some HIA. Also the experts were not saying that the period of actual HIA was either 15 minutes or 20 minutes, but that it was between 15 and 20 minutes. It could have been 16 minutes, or 19 minutes, for example.
It might be argued therefore that in some cases a claimant is advantaged by uncertainty in the expert evidence. Thus, if the evidence establishes that a child has suffered CP due to a period of HIA, a part of that period being non-negligent and the other part being negligent, but the evidence can only establish that the negligent period caused either some or all of the cerebral palsy, the claim will succeed, and it seems, compensation will be awarded for all the cerebral palsy suffered. On the other hand if the evidence establishes exactly the duration of the negligent and non-negligent parts of the period of HIA, and that the child would have suffered some CP even without the negligence, but less severe CP than he has in fact suffered, then compensation will be awarded only for the additional injury caused by the negligent delay.
This judgment does not address other questions such as how the courts should approach cases where the uncertainty is greater, namely that but for the period of delay the Claimant may have suffered all, some or even none of the injury he did in fact suffer. Or where the uncertainty is not about the period of negligent exposure to a damaging cause but about the extent of the injury caused by that exposure.